Thanks for the warnings. Yes as I go up in voltage, I will definitely not be able to rely on any controller-warnings to determine when to recharge. However right now I'm in the process of trying to install a no-name meter that measures real-time voltage and current: https://item.jd.com/15359070342.html
. When that's done I will know both the open circuit and the under-load voltages. For this, I'm going to be cutting and joining wires outside the controller, not getting inside the controller itself.
Since we're on this topic, maybe I just share my thoughts for any feedback as I don't know if it's been done the way I'm thinking before. This meter needs to run 3 wires from inside the bike to my dash where I'm going to mount the meter. Further it needs 2 more wires for power (between 4 and 28V) which I'm going to take from a 9V battery, located on or near the dash. The 3 wires I need from inside the bike are the 2 sides of the shunt, and the V++ wire (the high voltage wire between the battery and the controller/motor. The shunt needs to be inserted in the V-- wire (the low voltage wire between the battery and the motor/controller) for indirectly measuring the current. So I need to cut and reattach that V-- wire to the 2 sides of the shunt.
There are a couple of things I want, that I think I have a solution for:
1) I want to have the wires grouped together in some kind of outer sheathing, so I don't have to run 3 individual wires from internal to the bike, up to the dash
2) I want the system to be easily connectable/disconnectable so I can take the meter off my bike when I'm not there and just not mount it if it rains.
My solution is to buy any cable that has multiple (at least 3) wires inside and of about 1.5m in length that has a male connector on one end, and equivalent female connector of the same type on the other end. I'm going to cut this cable in the middle at the appropriate position exposing the wires inside. The longer side of this cut cable I'm going to solder them to the appropriate wires inside the bike, and I'll run the side with the connector attached, out to the dash. The other side of this cable I'm going to solder to the appropriate wires inside the meter, with the opposite connector attached to the other end. Now when I connect these two together the appropriate wires in the bike will be connected to the appropriate wires in the meter. And I can disconnect the meter and take it off the bike as I wish. I'm thinking of buying an ethernet RJ45 extension cable with male and female connectors on either side, because ethernet has 8 twisted pairs inside, more than enough for the 3 wires that I need.
Any comments on whether this plan will work?